Exposure of the dental pulp due to caries and/or iatrogenic factors occurs in the practice of dentistry and results in inflammation of the pulp tissue and can cause necrosis and death of that tissue. Medicaments such as Ca(OH)2 containing materials, if placed directly on the pulp when the tooth is restored are often the most appropriate means of treatment to assure healing. These materials are suggested as they have previously been demonstrated to be effective in treating pulp exposures. This effectiveness is judged on the presence of a reparative dentin bridge over the exposure site and is associated with the healing of the adjacent pulpal tissue. However, the unassisted healing capacity of the dental pulp is not known and should be investigated. The proposed research will investigate the pulpal response to the placement of inert Teflon R sealed over exposed dental pulp tissue. In doing so, the regenerative capacity of the dental pulp following a precise means of exposure without the direct effect of a dental material will be evaluated. In the proposed study three adult Rhesus monkeys will be used to provide ninety teeth. Class 5 cavity preparations will be prepared on the buccal surfaces of each of these teeth. The pulp will be exposed and in one group a Teflon R disk, and in a second group a commercially available Ca(OH)2 containing pulp capping agent will be placed directly in contact with the pulp. All cavities will then be sealed as stated and left undisturbed for either 3 days, 5 or 8 weeks. All time periods and treatment types will be evenly distributed in each of the three monkeys. Following sacrifice, careful removal of the teeth, demineralization, serial sectioning and staining with either hematoxylin and eosin or Masson's trichrome and McKay's modified Preston for bacteria, light microscopic histologic evaluation of the tissue will be undertaken to evaluate the type and extent of pulp healing adjacent to the Teflon R and Ca(OH)2 groups. This information will provide valuable insight to the unassisted reparative capacities of the dental pulp.